Why are the front brakes better then the rear brakes?

Carsightings · March 29th, 2006, 10:20 AM

i have noticed that on most mercs (non amg) the front discs are drilled yet the rear are not. Its the same story with the c6 corvette the front brakes are bigger than the rear ones.

what is the reason for this?

fbc · March 29th, 2006, 10:39 AM

You'll find this on most cars. It's due to physics - when decelerating the weight and energy transfers to the front of the vehicle, as a result front brakes are larger since they have more energy to cope with, and that extra weight also gives the front wheels extra grip and thus more braking ability.

Anyone feel free to correct me images/smilies/smile.gif

mmap · March 29th, 2006, 11:28 AM

Quote:

Originally Posted by fbc

Anyone feel free to correct me images/smilies/smile.gif

Why??

flyingfridge · March 29th, 2006, 12:15 PM

Quote:

Originally Posted by fbc

You'll find this on most cars. It's due to physics - when decelerating the weight and energy transfers to the front of the vehicle, as a result front brakes are larger since they have more energy to cope with, and that extra weight also gives the front wheels extra grip and thus more braking ability.

Anyone feel free to correct me images/smilies/smile.gif

Spot on correctamondo, no correctioning required images/smilies/thumbsup.gif

and if you want to pick me out for making up words, i claim shakespeare did it and so will i images/smilies/wink.gif

FATMOUSE · March 29th, 2006, 01:29 PM

If you want a quick reason why:

Download the LFS demo. Get on the drag strip or any long straight, with really strong brakes and a really high rear bias. Get to top speed, then brake hard.

Let me know how that works out for you.

Redliner · March 29th, 2006, 01:37 PM

Quote:

Originally Posted by FATMOUSE

If you want a quick reason why:

Download the LFS demo. Get on the drag strip or any long straight, with really strong brakes and a really high rear bias. Get to top speed, then brake hard.

Let me know how that works out for you.

I was just going to point that out. Look at motorcycle brakes (specially sport models) where the weight transfer (and the difference between front/rear) is even more pronounced: You have a rather small rear disc brake and two huge discs in the front.

bone · March 29th, 2006, 01:37 PM

Quote:

Originally Posted by fbc

You'll find this on most cars. It's due to physics - when decelerating the weight and energy transfers to the front of the vehicle, as a result front brakes are larger since they have more energy to cope with, and that extra weight also gives the front wheels extra grip and thus more braking ability.

and IF you set up the rear brakes equal to the front brakes, the rear brakes would lock up under (medium)hard braking (granted there's no ABS), which you don't want either

Carsightings · March 31st, 2006, 01:52 PM

thanks

Z Draci · April 1st, 2006, 09:33 PM

The front brake are bigger than the rears because the brake balance is more biased towards the front. When front brakes > rear brakes the car tends to understeer more into a turn. When front brakes < rear brakes the rear of the car will lock up first and cause the backend to slide around (oversteer). The former is safer for road cars. Since the front brakes do more work they are bigger (or "better").

Race cars have a more neutral balance because race car drivers demand a tiny bit of oversteer while turning in. (watch the Australian GP practice sessions!) Also, race cars have manually adjustable brake balance valves. Drivers can change the balance during the race.

Redliner · April 2nd, 2006, 07:32 AM

Quote:

Originally Posted by Z Draci

The front brake are bigger than the rears because the brake balance is more biased towards the front. When front brakes > rear brakes the car tends to understeer more into a turn. When front brakes < rear brakes the rear of the car will lock up first and cause the backend to slide around (oversteer). The former is safer for road cars. Since the front brakes do more work they are bigger (or "better").

Race cars have a more neutral balance because race car drivers demand a tiny bit of oversteer while turning in. (watch the Australian GP practice sessions!) Also, race cars have manually adjustable brake balance valves. Drivers can change the balance during the race.

But even race cars have bigger front brakes, because they should be stronger due to weight transfer, right? Please correct me if I´m wrong.

Z Draci · April 4th, 2006, 09:30 AM

Quote:

Originally Posted by Redliner

Quote:

Originally Posted by Z Draci

The front brake are bigger than the rears because the brake balance is more biased towards the front. When front brakes > rear brakes the car tends to understeer more into a turn. When front brakes < rear brakes the rear of the car will lock up first and cause the backend to slide around (oversteer). The former is safer for road cars. Since the front brakes do more work they are bigger (or "better").

Race cars have a more neutral balance because race car drivers demand a tiny bit of oversteer while turning in. (watch the Australian GP practice sessions!) Also, race cars have manually adjustable brake balance valves. Drivers can change the balance during the race.

But even race cars have bigger front brakes, because they should be stronger due to weight transfer, right? Please correct me if I´m wrong.

Yes, you're correct! Even if the static weight balance from front to rear is a perfect 50:50 when the car is braking that weight balance can shift biased towards the front. So the front brakes need to have a higher braking force relative to the rear. That's why the front brakes are bigger in all cars and motorcycles.

Dark_Templer_102 · April 4th, 2006, 03:15 PM

Also, the cross-drilled merc brakes are usually brembos up front and the rear....well its just normal merc brakes. Why are they cross-drilled? Prob to make them "look" agressive....cross-drilling really doesn't do much compared to normal vented...

Z Draci · April 5th, 2006, 11:25 AM

The holes in cross-drilled rotors vent the gas produced from the brake pads. If the rotor is solid, the gas can act as a layer between the pad and rotor surface--which people claim can reduce braking force. Most people now say that cross-drilled rotors can cause uneven rotor wear and has problems with uniformity (causes vibrations and uneven braking force).

This is why slotted rotors are the norm for evacuating brake pad gases. Also, street driven cars do not necessarily need cross-drilled or slotted rotors. It is only useful during periods of strong, prolonged braking where brakes can fade due to overheating.

For street cars they usually use slotted or vented rotors just for looks.

wahaha · April 12th, 2006, 08:57 AM

Drilling front rotors weakens them and can cause cracks. Some have shattered, and it's not worth it because there's also less surface area and friction for stopping power. It doesn't make up for the supposed "weight savings".

If you want performace rotors, get slotted. I have them. Sounds cool when stopping too. Flings water out the channels as well.

ArosaMike · April 12th, 2006, 03:45 PM

Quote:

Originally Posted by wahaha

Drilling front rotors weakens them and can cause cracks. Some have shattered, and it's not worth it because there's also less surface area and friction for stopping power. It doesn't make up for the supposed "weight savings".

If you want performace rotors, get slotted. I have them. Sounds cool when stopping too. Flings water out the channels as well.

That's only in very poorly designed discs. If it's all modelled correctly before being made, there is no reason why the disc should shatter. Also...the holes are there for lightness.....as stated they're there for getting rid of the dust images/smilies/wink.gif

The_Finn · April 12th, 2006, 04:22 PM

current pad technology doesn't have the issue with outgassing that older brakes used to have even in racing applications so at this point cross drilling and venting is somewhat useless beyong getting rid of brake dust and heat disipation

TF

Chupacabras · April 12th, 2006, 05:55 PM

Its the same with my DH bike images/smilies/biggrin.gif

March 29th, 2006, 10:20 AM	#1
Carsightings Joined: Dec 25th, 2005 Last Online: July 25th, 2006 Location: Israel Posts: 1,017 Rep Power: 0	Why are the front brakes better then the rear brakes? i have noticed that on most mercs (non amg) the front discs are drilled yet the rear are not. Its the same story with the c6 corvette the front brakes are bigger than the rear ones. what is the reason for this? __________________ Some one has been fucking with my profile.

March 29th, 2006, 10:39 AM	#2
fbc Mantastic! Joined: Jan 8th, 2005 Last Online: Yesterday Location: Melbourne, Australia Age: 33 Posts: 10,346 Car: 2006 MY07 Astra SRi Turbo Rep Power: 77	You'll find this on most cars. It's due to physics - when decelerating the weight and energy transfers to the front of the vehicle, as a result front brakes are larger since they have more energy to cope with, and that extra weight also gives the front wheels extra grip and thus more braking ability. Anyone feel free to correct me __________________ www.sniffpetrol.com

March 29th, 2006, 01:29 PM	#5
FATMOUSE Joined: Jun 30th, 2005 Last Online: Yesterday Location: NYC Posts: 2,992 Rep Power: 28	If you want a quick reason why: Download the LFS demo. Get on the drag strip or any long straight, with really strong brakes and a really high rear bias. Get to top speed, then brake hard. Let me know how that works out for you. __________________ woohoo someone changed my sig

March 31st, 2006, 01:52 PM	#8
Carsightings Joined: Dec 25th, 2005 Last Online: July 25th, 2006 Location: Israel Posts: 1,017 Rep Power: 0	thanks __________________ Some one has been fucking with my profile.

April 1st, 2006, 09:33 PM	#9
Z Draci Joined: Mar 31st, 2005 Last Online: May 23rd, 2007 Location: Glendora/Riverside, CA Posts: 915 Rep Power: 0	The front brake are bigger than the rears because the brake balance is more biased towards the front. When front brakes > rear brakes the car tends to understeer more into a turn. When front brakes < rear brakes the rear of the car will lock up first and cause the backend to slide around (oversteer). The former is safer for road cars. Since the front brakes do more work they are bigger (or "better"). Race cars have a more neutral balance because race car drivers demand a tiny bit of oversteer while turning in. (watch the Australian GP practice sessions!) Also, race cars have manually adjustable brake balance valves. Drivers can change the balance during the race. __________________ *"The car is the closest thing we will ever create to something that is alive." - Sir William Lyons*

April 4th, 2006, 03:15 PM	#12
Dark_Templer_102 Joined: Jul 17th, 2004 Last Online: 07:32 AM Location: Alpharetta, Georgia. U.S.A Posts: 1,663 Car: Subaru Legacy GT Rep Power: 0	Also, the cross-drilled merc brakes are usually brembos up front and the rear....well its just normal merc brakes. Why are they cross-drilled? Prob to make them "look" agressive....cross-drilling really doesn't do much compared to normal vented... __________________

April 5th, 2006, 11:25 AM	#13
Z Draci Joined: Mar 31st, 2005 Last Online: May 23rd, 2007 Location: Glendora/Riverside, CA Posts: 915 Rep Power: 0	The holes in cross-drilled rotors vent the gas produced from the brake pads. If the rotor is solid, the gas can act as a layer between the pad and rotor surface--which people claim can reduce braking force. Most people now say that cross-drilled rotors can cause uneven rotor wear and has problems with uniformity (causes vibrations and uneven braking force). This is why slotted rotors are the norm for evacuating brake pad gases. Also, street driven cars do not necessarily need cross-drilled or slotted rotors. It is only useful during periods of strong, prolonged braking where brakes can fade due to overheating. For street cars they usually use slotted or vented rotors just for looks. __________________ *"The car is the closest thing we will ever create to something that is alive." - Sir William Lyons*

April 12th, 2006, 08:57 AM	#14
wahaha Joined: Jan 2nd, 2006 Last Online: November 17th, 2008 Location: Univ. of Michigan Posts: 107 Car: Audi A6 2.7T, don't need anything more Rep Power: 0	Drilling front rotors weakens them and can cause cracks. Some have shattered, and it's not worth it because there's also less surface area and friction for stopping power. It doesn't make up for the supposed "weight savings". If you want performace rotors, get slotted. I have them. Sounds cool when stopping too. Flings water out the channels as well. __________________

April 12th, 2006, 04:22 PM	#16
The_Finn Joined: Feb 7th, 2005 Last Online: 04:45 AM Location: Worcestersheshershire MA Age: 27 Posts: 2,395 Car: 1988 Mazda 323 GTX / 1997 Saab 900s Rep Power: 31	current pad technology doesn't have the issue with outgassing that older brakes used to have even in racing applications so at this point cross drilling and venting is somewhat useless beyong getting rid of brake dust and heat disipation TF __________________ Proud owner of a 1988 mazda 323 GTX: The ~~poor~~ rich mans evo... “Auto racing, bull fighting, and mountain climbing are the only real sports ... all others are games.” ~Ernest Hemingway~ It's all about having the right priorities. You can sleep in your car but you can't race your house -\|- Basically i go accurately and on special lines

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